Will this method of raycasting work securely?

I want to make guns which use raycasting whilst keeping the amount of processing needed to be as low as possible on the server and I'm trying to think of some workarounds to reduce the amount that remote events/functions need to do. I also want to make sure it's still secure and performs well.

I thought of calculating the raycasts on the client side and then firing the remote event for wherever the raycast hit on the server. This means that the server should do less but I'm concerned about security. Would it be easy for people to change their client so they can abuse this? am I better off letting the server calculate all the raycasts?

Thanks